Laravel核心——服務容器的細節(jié)特性

AprilJ 發(fā)布于2019-06-27 16:35 / 3352人閱讀

摘要：前言首先歡迎關(guān)注我的博客在前面幾個博客中，我詳細講了容器各個功能的使用綁定的源碼解析的源碼，今天這篇博客會詳細介紹容器的一些細節(jié)，一些特性，以便更好地掌握容器的功能。

前言

首先歡迎關(guān)注我的博客： www.leoyang90.cn

在前面幾個博客中，我詳細講了 Ioc 容器各個功能的使用、綁定的源碼、解析的源碼，今天這篇博客會詳細介紹 Ioc 容器的一些細節(jié)，一些特性，以便更好地掌握容器的功能。

注：本文使用的測試類與測試對象都取自 laravel 的單元測試文件src/illuminate/tests/Container/ContainerTest.php

rebind綁定特性 rebind 在綁定之前

instance 和普通 bind 綁定一樣，當重新綁定的時候都會調(diào)用 rebind 回調(diào)函數(shù)，但是有趣的是，對于普通 bind 綁定來說，rebind 回調(diào)函數(shù)被調(diào)用的條件是當前接口被解析過：

public function testReboundListeners()
{
    unset($_SERVER["__test.rebind"]);

    $container = new Container;
    $container->rebinding("foo", function () {
        $_SERVER["__test.rebind"] = true;
    });
    $container->bind("foo", function () {
    });
    $container->make("foo");
    $container->bind("foo", function () {
    });

    $this->assertTrue($_SERVER["__test.rebind"]);
}

所以遇到下面這樣的情況,rebinding 的回調(diào)函數(shù)是不會調(diào)用的：

public function testReboundListeners()
{
    unset($_SERVER["__test.rebind"]);

    $container = new Container;
    $container->rebinding("foo", function () {
        $_SERVER["__test.rebind"] = true;
    });
    $container->bind("foo", function () {
    });
    $container->bind("foo", function () {
    });

    $this->assertFalse(isset($_SERVER["__test.rebind"]));
}

有趣的是對于 instance 綁定：

public function testReboundListeners()
{
    unset($_SERVER["__test.rebind"]);

    $container = new Container;
    $container->rebinding("foo", function () {
        $_SERVER["__test.rebind"] = true;
    });
    $container->bind("foo", function () {
    });
    $container->instance("foo", function () {
    });

    $this->assertTrue(isset($_SERVER["__test.rebind"]));
}

rebinding 回調(diào)函數(shù)卻是可以被調(diào)用的。其實原因就是 instance 源碼中 rebinding 回調(diào)函數(shù)調(diào)用的條件是 rebound 為真，而普通 bind 函數(shù)調(diào)用 rebinding 回調(diào)函數(shù)的條件是 resolved 為真. 目前筆者不是很清楚為什么要對 instance 和 bind 區(qū)別對待，希望有大牛指導。

rebind 在綁定之后

為了使得 rebind 回調(diào)函數(shù)在下一次的綁定中被激活，在 rebind 函數(shù)的源碼中，如果判斷當前對象已經(jīng)綁定過，那么將會立即解析：

public function rebinding($abstract, Closure $callback)
{
    $this->reboundCallbacks[$abstract = $this->getAlias($abstract)][] = $callback;
    
    if ($this->bound($abstract)) {
        return $this->make($abstract);
    }
}

單元測試代碼：

public function testReboundListeners1()
{
    unset($_SERVER["__test.rebind"]);

    $container = new Container;
    $container->bind("foo", function () {
        return "foo";
    });

    $container->resolving("foo", function () {
        $_SERVER["__test.rebind"] = true;
    });

    $container->rebinding("foo", function ($container,$object) {//會立即解析
        $container["foobar"] = $object."bar";
    });

    $this->assertTrue($_SERVER["__test.rebind"]);

    $container->bind("foo", function () {
    });

    $this->assertEquals("bar", $container["foobar"]);
}

resolving 特性 resolving 回調(diào)的類型

resolving 不僅可以針對接口執(zhí)行回調(diào)函數(shù)，還可以針對接口實現(xiàn)的類型進行回調(diào)函數(shù)。

public function testResolvingCallbacksAreCalledForType()
{
    $container = new Container;
    $container->resolving("StdClass", function ($object) {
        return $object->name = "taylor";
    });
    $container->bind("foo", function () {
          return new StdClass;
    });
    $instance = $container->make("foo");

    $this->assertEquals("taylor", $instance->name);
}
public function testResolvingCallbacksShouldBeFiredWhenCalledWithAliases()
{
    $container = new Container;
    $container->alias("StdClass", "std");
    $container->resolving("std", function ($object) {
        return $object->name = "taylor";
    });
    $container->bind("foo", function () {
        return new StdClass;
    });
    $instance = $container->make("foo");

    $this->assertEquals("taylor", $instance->name);
}

resolving 回調(diào)與 instance

前面講過，對于 singleton 綁定來說，resolving 回調(diào)函數(shù)僅僅運行一次，只在 singleton 第一次解析的時候才會調(diào)用。如果我們利用 instance 直接綁定類的對象，不需要解析，那么 resolving 回調(diào)函數(shù)將不會被調(diào)用：

public function testResolvingCallbacksAreCalledForSpecificAbstracts()
{
    $container = new Container;
    $container->resolving("foo", function ($object) {
        return $object->name = "taylor";
    });
    $obj = new StdClass;
    $container->instance("foo", $obj);
    $instance = $container->make("foo");

    $this->assertFalse(isset($instance->name));
}

extend 擴展特性

extend 用于擴展綁定對象的功能，對于普通綁定來說，這個函數(shù)的位置很靈活：

在綁定前擴展

public function testExtendIsLazyInitialized()
{
    ContainerLazyExtendStub::$initialized = false;
    
    $container = new Container;      
    $container->extend("IlluminateTestsContainerContainerLazyExtendStub", function ($obj, $container) {
        $obj->init();
        return $obj;   
    });    
    $container->bind("IlluminateTestsContainerContainerLazyExtendStub"); 

    $this->assertFalse(ContainerLazyExtendStub::$initialized);   
    $container->make("IlluminateTestsContainerContainerLazyExtendStub");   
    $this->assertTrue(ContainerLazyExtendStub::$initialized);
}

在綁定后解析前擴展

public function testExtendIsLazyInitialized()
{
    ContainerLazyExtendStub::$initialized = false;
    
    $container = new Container;   
    $container->bind("IlluminateTestsContainerContainerLazyExtendStub");    
    $container->extend("IlluminateTestsContainerContainerLazyExtendStub", function ($obj, $container) {
        $obj->init();
        return $obj;   
    });    

    $this->assertFalse(ContainerLazyExtendStub::$initialized);   
    $container->make("IlluminateTestsContainerContainerLazyExtendStub");   
    $this->assertTrue(ContainerLazyExtendStub::$initialized);
}

在解析后擴展

public function testExtendIsLazyInitialized()
{
    ContainerLazyExtendStub::$initialized = false;
    
    $container = new Container;   
    $container->bind("IlluminateTestsContainerContainerLazyExtendStub");         
    
    $container->make("IlluminateTestsContainerContainerLazyExtendStub"); 
    $this->assertFalse(ContainerLazyExtendStub::$initialized);
    
    $container->extend("IlluminateTestsContainerContainerLazyExtendStub", function ($obj, $container) {
        $obj->init();
        return $obj;   
    });
    $this->assertFalse(ContainerLazyExtendStub::$initialized);  
      
    $container->make("IlluminateTestsContainerContainerLazyExtendStub"); 
    $this->assertTrue(ContainerLazyExtendStub::$initialized);
}

可以看出，無論在哪個位置，extend 擴展都有 lazy 初始化的特點，也就是使用 extend 函數(shù)并不會立即起作用，而是要等到 make 解析才會激活。

extend 與 instance 綁定

對于 instance 綁定來說，暫時 extend 的位置需要位于 instance 之后才會起作用，并且會立即起作用，沒有 lazy 的特點：

public function testExtendInstancesArePreserved()
{
    $container = new Container;

    $obj = new StdClass;
    $obj->foo = "foo";
    $container->instance("foo", $obj);
    $container->extend("foo", function ($obj, $container) {
        $obj->bar = "baz";

        return $obj;
    });

    $this->assertEquals("foo", $container->make("foo")->foo);
    $this->assertEquals("baz", $container->make("foo")->bar);
}

extend 綁定與 rebind 回調(diào)

無論擴展對象是 instance 綁定還是 bind 綁定，extend 都會啟動 rebind 回調(diào)函數(shù)：

public function testExtendReBindingInstance()
{
    $_SERVER["_test_rebind"] = false;

    $container = new Container;
    $container->rebinding("foo",function (){
        $_SERVER["_test_rebind"] = true;
    });

    $obj = new StdClass;
    $container->instance("foo",$obj);

    $container->make("foo");

    $container->extend("foo", function ($obj, $container) {
        return $obj;
    });

    this->assertTrue($_SERVER["_test_rebind"]);
}

public function testExtendReBinding()
{
    $_SERVER["_test_rebind"] = false;

    $container = new Container;
    $container->rebinding("foo",function (){
        $_SERVER["_test_rebind"] = true;
    });
    $container->bind("foo",function (){
        $obj = new StdClass;

        return $obj;
    });

    $container->make("foo");

    $container->extend("foo", function ($obj, $container) {
        return $obj;
    });

    this->assertFalse($_SERVER["_test_rebind"]);
}

contextual 綁定特性 contextual 在綁定前

contextual 綁定不僅可以與 bind 綁定合作，相互不干擾，還可以與 instance 綁定相互合作。而且 instance 的位置也很靈活，可以在 contextual 綁定前，也可以在contextual 綁定后：

public function testContextualBindingWorksForExistingInstancedBindings()
{
    $container = new Container;

    $container->instance("IlluminateTestsContainerIContainerContractStub", new ContainerImplementationStub);

    $container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("IlluminateTestsContainerIContainerContractStub")->give("IlluminateTestsContainerContainerImplementationStubTwo");

    $this->assertInstanceOf(
             "IlluminateTestsContainerContainerImplementationStubTwo",
             $container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
     );
}

contextual 在綁定后

public function testContextualBindingWorksForNewlyInstancedBindings()
{
    $container = new Container;

    $container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("IlluminateTestsContainerIContainerContractStub")->give("IlluminateTestsContainerContainerImplementationStubTwo");

    $container->instance("IlluminateTestsContainerIContainerContractStub", new ContainerImplementationStub);

    $this->assertInstanceOf(
            "IlluminateTestsContainerContainerImplementationStubTwo",
        $container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
    );
}

contextual 綁定與別名

contextual 綁定也可以在別名上進行，無論賦予別名的位置是 contextual 的前面還是后面：

public function testContextualBindingDoesntOverrideNonContextualResolution()
{
    $container = new Container;

    $container->instance("stub", new ContainerImplementationStub);
    $container->alias("stub", "IlluminateTestsContainerIContainerContractStub");

    $container->when("IlluminateTestsContainerContainerTestContextInjectTwo")->needs("IlluminateTestsContainerIContainerContractStub")->give("IlluminateTestsContainerContainerImplementationStubTwo");

    $this->assertInstanceOf(
            "IlluminateTestsContainerContainerImplementationStubTwo",
            $container->make("IlluminateTestsContainerContainerTestContextInjectTwo")->impl
        );

    $this->assertInstanceOf(
            "IlluminateTestsContainerContainerImplementationStub",
            $container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
    );
}

public function testContextualBindingWorksOnNewAliasedBindings()
{
    $container = new Container;

    $container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("IlluminateTestsContainerIContainerContractStub")->give("IlluminateTestsContainerContainerImplementationStubTwo");

    $container->bind("stub", ContainerImplementationStub::class);
    $container->alias("stub", "IlluminateTestsContainerIContainerContractStub");

    $this->assertInstanceOf(
          "IlluminateTestsContainerContainerImplementationStubTwo",
          $container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
    );
}

爭議

目前比較有爭議的是下面的情況：

public function testContextualBindingWorksOnExistingAliasedInstances()
{
    $container = new Container;

    $container->alias("IlluminateTestsContainerIContainerContractStub", "stub");
    $container->instance("stub", new ContainerImplementationStub);

    $container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("stub")->give("IlluminateTestsContainerContainerImplementationStubTwo");

    $this->assertInstanceOf(
        "IlluminateTestsContainerContainerImplementationStubTwo",
        $container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
    ); 
}

由于instance的特性，當別名被綁定到其他對象上時，別名 stub 已經(jīng)失去了與 IlluminateTestsContainerIContainerContractStub 之間的關(guān)系，因此不能使用 stub 代替作上下文綁定。
但是另一方面：

public function testContextualBindingWorksOnBoundAlias()
{
    $container = new Container;

    $container->alias("IlluminateTestsContainerIContainerContractStub", "stub");
    $container->bind("stub", ContainerImplementationStub::class);

    $container->when("IlluminateTestsContainerContainerTestContextInjectOne")->needs("stub")->give("IlluminateTestsContainerContainerImplementationStubTwo");

    $this->assertInstanceOf(
        "IlluminateTestsContainerContainerImplementationStubTwo",
        $container->make("IlluminateTestsContainerContainerTestContextInjectOne")->impl
    ); 
}

代碼只是從 instance 綁定改為 bind 綁定，由于 bind 綁定只切斷了別名中的 alias 數(shù)組的聯(lián)系，并沒有斷絕abstractAlias數(shù)組的聯(lián)系，因此這段代碼卻可以通過，很讓人難以理解。本人在給 Taylor Otwell 提出 PR 時，作者原話為“I"m not making any of these changes to the container on a patch release.”。也許，在以后(5.5或以后)版本作者會更新這里的邏輯，我們就可以看看服務容器對別名綁定的態(tài)度了，大家也最好不要這樣用。

服務容器中的閉包函數(shù)參數(shù)

服務容器中很多函數(shù)都有閉包函數(shù)，這些閉包函數(shù)可以放入特定的參數(shù)，在綁定或者解析過程中，這些參數(shù)會被服務容器自動帶入各種類對象或者服務容器實例。

bind 閉包參數(shù)

public function testAliasesWithArrayOfParameters()
{
    $container = new Container;    
    $container->bind("foo", function ($app, $config) {
        return $config;    
    });    

    $container->alias("foo", "baz");    
    $this->assertEquals([1, 2, 3], $container->makeWith("baz", [1, 2, 3]));
}

extend 閉包參數(shù)

public function testExtendedBindings()
{
    $container = new Container;    
    $container["foo"] = "foo’;    
    $container->extend("foo", function ($old, $container) {
        return $old."bar’;    
    });
   
    $this->assertEquals("foobar", $container->make("foo"));
    
    $container = new Container;
    
    $container->singleton("foo", function () {
        return (object) ["name" => "taylor"];    
    });    
    $container->extend("foo", function ($old, $container) {
        $old->age = 26;
        return $old;    
    });
    
    $result = $container->make("foo");
    $this->assertEquals("taylor", $result->name);    
    $this->assertEquals(26, $result->age);   
    $this->assertSame($result, $container->make("foo"));
}

bindmethod 閉包參數(shù)

public function testCallWithBoundMethod()
{
    $container = new Container;
    $container->bindMethod("IlluminateTestsContainerContainerTestCallStub@unresolvable", function ($stub,$container) {
        $container["foo"] = "foo";
        return $stub->unresolvable("foo", "bar");
    });
    $result = $container->call("IlluminateTestsContainerContainerTestCallStub@unresolvable");
    $this->assertEquals(["foo", "bar"], $result);
    $this->assertEquals("foo",$container["foo"]);
}

resolve 閉包參數(shù)

public function testResolvingCallbacksAreCalledForSpecificAbstracts()
{
     $container = new Container;
     $container->resolving("foo", function ($object，$container) {
         return $object->name = "taylor";
     });
 
     $container->bind("foo", function () {
        return new StdClass;
     });
     $instance = $container->make("foo");

     $this->assertEquals("taylor", $instance->name);
}

rebinding 閉包參數(shù)

public function testReboundListeners()
{
    $container = new Container;
    $container->bind("foo", function () {
        return "foo";
    });
  
    $container->rebinding("foo", function ($container,$object) {
         $container["bar"] = $object."bar";
    });
  
    $container->bind("foo", function () {
    });

    $this->assertEquals("bar",$container["foobar"]);
}

GPU云服務器云服務器服務器集群的特性類的特性 linux的特性 spark的特性

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【C語言進階學習】一、數(shù)據(jù)的存儲 (深度剖析數(shù)據(jù)在內(nèi)存中的存儲)

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